The present invention relates to roller reamers, used in connection with earth boring tools such as are used in oil and gas drilling.
Roller reamers are typically used in drill strings, behind a drill bit for earth boring and drilling. The reamer has an elongate, generally cylindrical body. The reamer body is provided with a plurality of circumferencially spaced pockets: three or four are typically provided, and in each of the pockets there is provided a roller, which may have teeth on it, the purpose of the roller reamer being to enlarge or maintain the size of the bore hole and to stabilize the position of the drill bit, and therefore its direction. For this reason, the roller reamer is also designated as a stabilizer.
The rollers are journalled on shafts, and the shafts, in turn, are supported in bearing blocks which are carried by the reamer body. Typically, slots extend in the reamer body generally axially, above and below the pocket, and the bearing blocks are positioned in the slots. Since the centrifugal forces produced by rotation of the drill string tend to cause the bearing blocks to move radially outwardly, provision is made to prevent such radial outward movement.
Wagnon, et al., U.S. Pat. No. 3,627,068, discloses a roller reamer construction of the above described type, in which the slot for the bearing block is undercut, and the bearing block has flanges entering into the undercut portion of the reamer body. The slot is axially elongated, so that the bearing block may be moved away from the pocket, to permit introduction of the shaft and roller into the pocket, after which the bearing block is slid downwardly to telescope over the end of the shaft. A screw is threaded into the reamer body, to prevent movement of the bearing block away from the roller pocket.
Blau, et al., U.S. Pat. No. 4,428,626, discloses a reamer or stabilizer construction in which wear pads are provided with outwardly extending flanges which engage in an undercut portion of the stabilizer body, to prevent radial outward movement or "throwing" of them when the drill string is rotated.
Kloesel, Jr., et al., U.S. Pat. No. 3,303,900, and Terry, U.S. Pat. No. 4,190,124, disclose down-hole tools in which removable parts are joined by a dove tail connection.
Allison, et al., U.S. Pat. No. 4,262,760, provides a construction in which a bearing block is of generally cylindrical configuration, and is positioned in a corresponding cylindrical recess in the reamer body, with the axis of the recess and bearing block extending substantially radially of the reamer body. The bearing block engages the recess with an interference fit, and screws are additionally provided to secure the bearing block in place. Removal of the bearing block is achieved with a special tool, after removal of the screws.
Gray, U.S. Pat. No. 3,907,048, provides a stabilizer in which bearing blocks are friction fit into recesses in the stabilizer body, and are then additionally secured by screws or welding.
The prior art stabilizers have been difficult to assemble and disassemble, particularly with reference to the bearing blocks. Typically, as is given in some of the foregoing examples, there is a friction or interference fit between the bearing block and a corresponding slot or recess in the reamer or stabilizer body. For placement of the bearing block in position, or for removal of the bearing block from the reamer or stabilizer body, there is typically required the application of substantial force, and the utilization of two workmen. Either hammers or hydraulic tools are used to place the bearing blocks in position or remove them, thus requiring additional labor expenses and substantial forces to perform these operations; in some instances, additional equipment such as hydraulic tools are utilized, thereby adding to the expense of the assembly and disassembly of such roller reamers and stabilizers.